Table Of Contents

Backing Up the Database

Configuration

Command Line Utility

Recovery

mcdshadow Command Files

Backing Up the Database

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Revised: March 20, 2009, OL-17222-03

This chapter describes the Cisco Access Registrar (CAR) shadow backup facility, which ensures a consistent snapshot of CAR's database for backup purposes.

Because the CAR's database (called MCD) does a variety of memory caching, and might be active at any time, you cannot simply rely on doing system backups to protect the data in the database. At the time you run a system backup, there could be CAR operations in progress that cause the data copied to the system backup tape to be inconsistent and unusable as a replacement database.

To ensure a consistent backup, CAR uses a shadow backup facility. Once a day, at a configurable time, CAR suspends all activity to the database and takes a snapshot of the critical files. This snapshot is guaranteed to be a consistent view of the database, and it is preserved correctly on a system backup tape.

Configuration

The only configuration for this facility is through a single entry in the system Registry at $INSTALL/conf/car.conf is the registry path to this item.

This entry is a string that represents the time-of-day at which the shadow backup is scheduled to occur (in 24 hour HH:MM format). The default is 23:45.

When you remove this entry or set it to an illegal value (for example, anything that does not begin with a digit), backups are suppressed. The server is otherwise unaffected.

Command Line Utility

In addition to being available at a scheduled time of day, you can also force a shadow backup by using the mcdshadow utility located in the $INSTALL/bin directory. There are no command-line arguments.

This might take a few minutes to complete as a full copy of the database is created.

Recovery

When it is necessary to use the shadow backup to recover data, either because the regular working database has been corrupted by a system crash, or because the disk on which it resides has become corrupted, perform the following:

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Step 1 Stop all CAR servers.

Step 2 Make sure three files (mcddb.d01, mcddb.d02, and mcddb.d03) exist in the $INSTALL/data/db.bak directory.

Step 3 Copy the files into the $INSTALL/data/db directory. Do not move them because they might be needed again.

Step 4 Change directory to the $INSTALL/data/db directory.

cd  $INSTALL/data/db

Step 5 Rebuild the key files by entering the command:

$INSTALL/bin/keybuild mcddb

This might take several minutes.

Step 6 As a safety check, run $INSTALL/bin/dbcheck mcddb (UNIX) to verify the integrity of the database. Note, you must be user root to run dbcheck.

No errors should be detected.

mcdshadow Command Files

The mcdshadow command uses the files listed in Table 23-1.

Table 23-1 mcdshadow Files 

File	Description
mcddb.dbd	Template file that describes the low-level data schema for the Raima run-time library.
mcddb.k01 mcddb.k02 mcddb.k03	Key files that contain the data that is redundant with the data files. CAR does not back up these files because they can be completely rebuilt with the keybuild command.
mcdcd.d01 mcdcd.d02 mcdcd.d03	Data files that contain the backup.
mcdConfig.txt	Text file from which CAR configures the initial at-install-time database.
mcdschema.txt	Text file that contains a version number denoting the level of the schema contained in the dbd file. CAR will not attempt to open the database unless the number in this file matches a constant that is hard-coded in the libraries. If the result of the mcdshadow command (which uses copies of the data files) is divorced from its original mcdschema.txt, you will not be able to run CAR.
vista.taf vista.tcf vista.tjf	Working files used by the Raima run-time library to ensure transactional integrity.